I don't think there's really a bad time to visit California. It can be wet December to April, especially in Nor Cal but it's still nothing like the weather they have back East or in the Midwest. Also there's just a lot of people here all the time so the long lines and traffic are pretty much unavoidable. LA has the bad reputation for it but I've been in equally bad jams in San Francisco and in Sacramento. It just it what it is. The big tourist draws like Dinseyland are a little better on weekdays but then you might get a school trip or something if you go on a week day and it's actually worse so who knows. You're on a Sacramento fan board so there's some regional bias here... having lived in the SF area, the Sacramento area, and the So Cal area for significant stretches I would say that there's great things to see in all three. Here's how I would break it down:
Bay Area:
1] I also recommend Marin Headlands. The hiking there is easy (my parents would take my brother and I when we were toddlers) and there's a lot of cool history with all the WWII bunkers and gunhouses.
2] You can walk along the Embarcadero to Pier 39 which has a ton of restaurants and Fisherman's Wharf where you can get fresh sourdough and chowder at the Boudin Bakery.
3] If you're a movie fan, you might want to drive down Shady Lane in the town of Ross (near Marin Headlands) where they filmed some scenes for The Godfather. Coppola and Lucas are based in the area so they filmed a lot of scenes around here to substitute for other places. Ross is like a little hidden wooded grove with moss growing on the fences everywhere and trees that reach way out over the road so it feels like a tunnel. By October/November the trees should be full of Fall colors. There's also a short hike you can take here to Phoenix Lake. Speaking of Lucas, the Forest Moon of Endor is only a couple hours drive up the coast but that's probably too far out of the way for you. It'd be worth it though! The coastal redwoods are one of the highlights of California's natural beauty.
4] Check out Fort Point at the Southern base of the Golden Gate Bridge if you get a chance. It doesn't cost anything and it's one of the best views of the bridge (as seen in Hitchcock's Vertigo)
Sacramento:
1] If you do make it to Sacramento, get there early and go to Old Town on the river. You can learn about the history of the city there or just pop in and out of all the cool little novelty shops. At night they'll have live music and light shows certain times of year.
2] This is most likely out of the way, but Sunflower Drive-In in Fair Oaks is the first place I always go when I go back to visit my family. Get a Nutburger! You won't regret it! Also walk down Bridge Street over the pedestrian bridge to the American River bike trail. You can also rent a raft in Fair Oaks to float down the river nearby but that's more of a summer activity. In October/November I would think it'll be too cold. This is a really beautiful place to go for a walk though if you have the time.
Los Angeles/So Cal:
1] Personally I would avoid Disneyland right now because of the Star Wars land opening this Summer. You probably don't have much of a choice if the family is set on it but everything there is expensive already and the lines are going to be long. Knott's Berry Farm is nearby and offers a similar experience for a lot less money with smaller crowds.
2] Hollywood is tough to recommend as a tourist location. It's dirty and there's nothing to see there except people trying to sell you useless junk. Check the schedule for
The Hollywood Bowl though and see if you can work in a show you're interested in. It gets cold at night but you can bring blankets and food and wine. That's probably the best thing to do in the Hollywood Area. Or you could see what old movies they're playing at The Egyptian theater when you're in town.
3] Check out the Observatory in Griffith Park around sunset for one of the best views of Los Angeles. This is also free, you can drive most (all?) of the way up and it's a pretty spectacular spot (ie La La Land)
4] Also, on the other side of Griffith Park is the carousel (limited hours though so look up when it's open), the LA Zoo, the Travel Town mini train you can ride on and the Bridal Trails where you can take a guided horseback ride and look down on the San Fernando Valley -- this is my personal favorite spot in LA.
5] There's a lot of nice beaches to visit: Redondo, Newport, Laguna, etc. If you can make it all the way down there, Oceanside and Encinitas are beautiful if probably a little cold that time of year. Bring a sweater!
6] The Getty Center is a free art museum in the hills North of Santa Monica which also happens to be a masterpiece of modern architecture (you do have to pay $20 to park though). You could easily spend half a day there.
7] I'm planning a day trip for my parents around the Port of Los Angeles for early December right now which might also work out for you. You could visit the USS Iowa museum down there (a decommissioned WWII era Battleship), either the aquarium in Long Beach or the one in San Pedro, the Korean Friendship Bell overlooking the ocean in San Pedro, then drive through Palos Verdes up to Redondo Beach. A little further North, the drive up the coast through Malibu is also really nice.
9] Get yourself some street tacos! The best thing about LA is the abundance of amazing street tacos.
I'm sure there's a million other things you can do, those are just the first ones that come to mind. Vegas I don't know. I only go there when other people force me to. Walking the strip in the daytime isn't that exciting to me, but with everything lit up at night it can be pretty fun. I did just go to see the Grand Canyon a couple months ago. It's quite a long drive to get there so you might want to make that a separate trip. The only advice I have is to plan your trip so that you're there for sunset. The place really comes to life at sunset!